Adaptive modulation coding method and apparatus

ABSTRACT

An adaptive modulation coding method includes obtaining an estimated signal-to-interference-plus-noise ratio (SINR) and a packet error rate (PER) of a communication link of a user terminal; setting a first adjustment amount of the SINR of the communication link according to the PER of the communication link; calculating an effective SINR of the communication link according to the estimated SINR of the communication link and the first adjustment amount of the SINR of the communication link; and determining a modulation coding scheme of the communication link according to the effective SINR of the communication link.

This application is a continuation of U.S. patent application Ser. No.14/597,708, filed Jan. 15, 2015, which claims priority to Chinese PatentApplication No. 201410035685.3, filed Jan. 24, 2014, and all thebenefits accruing therefrom under 35 U.S.C. §119, the contents of whichin its entirety are herein incorporated by reference.

BACKGROUND

The present invention relates to wireless communication, and morespecifically, to an adaptive modulation coding method and an apparatusthereof.

In a wireless communication system, Adaptive Modulation Coding (AMC) iswidely used in order to enhance throughput of the whole system. AMC is atechnology which adaptively changes modulation and coding schemeaccording to channel condition. Its basic working principle is asfollows: a user at center of a cell, due to has bettersignal-to-interference-plus-noise ratio (SINR), is usually assigned ahigher modulation coding scheme or coding rate to enhance throughput,e.g., 64QAM, Turbo code with 3/4 code rate; whereas a user at edge of acell, whose SINR is low, is assigned lower modulation or coding rate(e.g., QPSK, Turbo code with 1/2 code rate) in order to ensure stabilityof the user. Using AMC has the following advantages: (1) user in abetter channel condition can be assigned higher modulation scheme andcoding rate, which can enhance average data throughput of the wholecell; (2) link level AMC that changes based on modulation coding schemecan reduce change in interference, as compared to the method thatcontrols transmission power; and (3) by combining AMC with time domainscheduling, user terminal is maintained in a low fading status byutilizing fast fading feature of the terminal.

A typical process for downlink AMC is as follows: user terminalestimates SINR of the downlink in real time, and reports the estimatedSINR information to a base station, the base station will determine adownlink modulation coding scheme to be used by user according to theSINR information reported by the user terminal. Such a working mechanismis widely used at present. If current system environment is ideal andthere is no interference during data transmission, then such a mechanismmay obtain relatively good performance. However, when there isinterference in system's working environment, SINR estimated by the userterminal may not be able to truly reflect status of the wirelesschannel, resulting in that the modulation coding scheme determinedaccording to this parameter is not the most appropriate. If modulationcoding scheme of the user terminal is set too high, it will cause alarge number of error codes, making system operation unstable. Ifmodulation coding scheme of the user terminal is set too low, throughputof the system will be wasted.

Thus, there is a need for a method that can flexibly adjust modulationcoding scheme employed by a user terminal in an interferenceenvironment.

SUMMARY

According to one aspect of the present invention, there is provided anadaptive modulation coding method, including obtaining an estimated SINRand a PER of a communication link of a user terminal; setting a firstadjustment amount of the SINR of the communication link according to thePER of the communication link; calculating an effective SINR of thecommunication link according to the estimated SINR of the communicationlink and the first adjustment amount of the SINR of the communicationlink; and determining a modulation coding scheme of the communicationlink according to the effective SINR of the communication link.

According to another aspect of the present invention, there is providedan adaptive modulation coding apparatus, including a first obtainingmodule configured to obtain an estimated SINR and a PER of acommunication link of a user terminal; a first setting module configuredto set a first adjustment amount of the SINR of the communication linkaccording to the PER of the communication link; a calculating moduleconfigured to calculate an effective SINR of the communication linkaccording to the estimated SINR of the communication link and the firstadjustment amount of the SINR of the communication link; and adetermining module configured to determine a modulation coding scheme ofthe communication link according to the effective SINR of thecommunication link.

The method and apparatus according to embodiments of the presentinvention can flexibly adjust modulation coding scheme employed by userin an interference environment.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some embodiments of the presentinvention in the accompanying drawings, the above and other objects,features and advantages of the present invention will become moreapparent, wherein the same reference generally refers to the samecomponents in the embodiments of the present invention.

FIG. 1 shows a block diagram of an exemplary computer system/serverwhich is applicable to implement the embodiments of the presentinvention;

FIG. 2 shows an adaptive modulation coding method according to anembodiment of the present invention;

FIG. 3 shows an adaptive modulation coding apparatus according to anembodiment of the present invention.

DETAILED DESCRIPTION

Exemplary embodiments will be described in more detail with reference tothe accompanying drawings, in which the preferable embodiments of thepresent invention have been illustrated. However, the present inventioncan be implemented in various manners, and thus should not be construedto be limited to the embodiments disclosed herein. On the contrary,those embodiments are provided for the thorough and completeunderstanding of the present invention, and completely conveying thescope of the present invention to those skilled in the art.

As will be appreciated by one skilled in the art, aspects of the presentinvention may be embodied as a system, method or computer programproduct. Accordingly, aspects of the present invention may take the formof an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present invention may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent invention may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

Aspects of the present invention are described below with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operations to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

Referring now to FIG. 1, in which an exemplary computer system/server 12which is applicable to implement the embodiments of the presentinvention is shown. Computer system/server 12 is only illustrative andis not intended to suggest any limitation as to the scope of use orfunctionality of embodiments of the invention described herein.

As shown in FIG. 1, computer system/server 12 is shown in the form of ageneral-purpose computing device. The components of computersystem/server 12 may include, but are not limited to, one or moreprocessors or processing units 16, a system memory 28, and a bus 18 thatcouples various system components including system memory 28 toprocessor 16.

Bus 18 represents one or more of any of several types of bus structures,including a memory bus or memory controller, a peripheral bus, anaccelerated graphics port, and a processor or local bus using any of avariety of bus architectures. By way of example, and not limitation,such architectures include Industry Standard Architecture (ISA) bus,Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, VideoElectronics Standards Association (VESA) local bus, and PeripheralComponent Interconnect (PCI) bus.

Computer system/server 12 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 12, and it includes both volatileand non-volatile media, removable and non-removable media.

System memory 28 can include computer system readable media in the formof volatile memory, such as random access memory (RAM) 30 and/or cachememory 32. Computer system/server 12 may further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 34 can be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a “hard drive”). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus 18 by one or more datamedia interfaces. As will be further depicted and described below,memory 28 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of embodiments of the invention.

Program/utility 40, having a set (at least one) of program modules 42,may be stored in memory 28 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 42 generally carry out the functions and/ormethodologies of embodiments of the invention as described herein.

Computer system/server 12 may also communicate with one or more externaldevices 14 such as a keyboard, a pointing device, a display 24, etc.;one or more devices that enable a user to interact with computersystem/server 12; and/or any devices (e.g., network card, modem, etc.)that enable computer system/server 12 to communicate with one or moreother computing devices. Such communication can occur via Input/Output(I/O) interfaces 22. Still yet, computer system/server 12 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 20. As depicted, network adapter 20communicates with the other components of computer system/server 12 viabus 18. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 12. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

With reference now to FIG. 2, which shows an adaptive modulation codingmethod according to an embodiment of the invention, comprising: in blockS201, obtaining an estimated SINR and a PER of a communication link of auser terminal; in block S202, setting a first adjustment amount of theSINR of the communication link according to the PER of the communicationlink; in block S203, calculating an effective SINR of the communicationlink according to the estimated SINR of the communication link and thefirst adjustment amount of the SINR of the communication link; in blockS204, determining a modulation coding scheme of the communication linkaccording to the effective SINR of the communication link.

In block S201, obtaining an estimated SINR and a PER of a communicationlink of a user terminal, wherein the SINR is a ratio of signal power tonoise power plus interference power, so it is necessary to estimate thepower of signal and the power of noise plus interference. In general,noise power and interference power are estimated together, and will notbe specifically distinguished. Methods for estimating SINR are usuallydivided into blind estimation method and pilot assisted estimationmethod according to characteristics of signal. The blind estimationmethod, without assistance of any pilot, generally utilizes methods ofsecond-order matrix, fourth-order matrix, or some subspace methods; ithas relatively lower estimation accuracy and relatively highercomplexity, accuracy thereof will be greatly reduced especially underinterference condition. The pilot assisted estimation method is toestimate SINR by using known pilots or a preamble sequence, which issimple in implementation and also has high estimation accuracy.Therefore, typical wireless communication systems all employ thisapproach to estimate SINR. For example, current popular 4G communicationsystem WiMAX or LTE will transmit a pilot sequence in its downlinksignal, which is generally a pseudorandom sequence to be used interminal's time synchronization, frequency synchronization etc.,therefore, this pilot sequence can be utilized to estimate downlink SINRthereof. The communication link comprises at least one of an uplink anda downlink. As for the uplink, generally in data region, pilots willalso be inserted to be used in channel estimation, therefore, thesepilots can be utilized to estimate uplink SINR. The estimated SINR ofdownlink is estimated at the terminal and is sent to a base station,therefore, the estimated SINR of the downlink can be obtained from thebase station. Those skilled in the art will appreciate that, PER (PacketError Rate) is a ratio of packets transmitted with error to totaltransmitted packets within a specified time, which can effectivelyreflect actual communication quality of a current wireless link; andspecific method for calculating PER will not be described here. Theestimated SINR and the PER of an uplink can be calculated at basestation side, the estimated SINR and the PER of a downlink need to becalculated at user terminal and fed back to the base station; thus, theestimated SINR and the PER of an uplink and a downlink can be obtainedfrom base station.

In block S202, setting a first adjustment amount of the SINR of thecommunication link according to the PER of the communication link. Ifthe PER is too high, it indicates that the actually set modulationcoding scheme is too high, that is, actual SINR is relatively high ascompared to the estimated SINR under interference condition, so it isnecessary to perform a certain amount of downward adjustment on theestimated SINR. If the PER is very low, it indicates that the actuallyset modulation coding scheme is too conservative, which instead willinfluence rate, i.e., actual SINR is relatively low as compared to theestimated SINR under interference condition; so it is necessary toperform a certain amount of upward adjustment on the estimated SINR. Forexample, when the PER is greater than 10%, the first adjustment amountmay be set as −2 dB; when the PER is between 10% and 3%, the firstadjustment amount may be set as −1 dB; when the PER is between 3% and1%, the first adjustment amount may be set as 0 dB; when the PER is lessthan 1%, the first adjustment amount may be set as 1 dB. The firstadjustment amount of the SINR is an accumulative adjustment on theestimated SINR along a continuous statistic collecting time axis; forexample, initial value of the first adjustment amount is 0, if the PERcounted in a current time period is 5%, then the first adjustment amountis adjusted to −2 dB; if the PER counted in a subsequent time period is2%, then it is necessary to further adjust the first adjustment amountby −1 dB; i.e., adjust it to −3 dB.

In block S203, calculating an effective SINR of the communication linkaccording to the estimated SINR of the communication link and the firstadjustment amount of the SINR of the communication link. According to anembodiment of the invention, for case of a downlink, further comprises:obtaining the estimated SINR and the PER of the downlink of the userterminal, wherein the estimated SINR of the downlink is estimated at theterminal and the estimated result is sent to a base station, therefore,the estimated SINR of the downlink can be obtained from the basestation; setting the first adjustment amount of the SINR of the downlinkaccording to the PER of the downlink; calculating the effective SINR ofthe downlink according to the estimated SINR of the downlink and thefirst adjustment amount of the SINR of the downlink.

According to an embodiment of the invention, the effective SINR of thedownlink is calculated according to the following formula:SINR_eff_(downlink)=SINR_est_(downlink)+SINR_per_(downlink), whereinSINR_eff_(downlink) represents the effective SINR of the downlink,SINR_est_(downlink) represents the estimated SINR of the downlink, andSINR_per_(downlink) represents the first adjustment amount of the SINRof the downlink.

According to an embodiment of the invention, for case of the uplink,further comprises: obtaining the estimated SINR and the PER of theuplink of the user terminal, wherein the estimated SINR and the PER ofthe uplink are calculated by base station, therefore, they can beobtained from the base station; setting the first adjustment amount ofthe SINR of the uplink according to the PER of the uplink, for specificmethod thereof, reference may be made to the above description, whichwill not be repeated here for brevity; calculating the effective SINR ofthe uplink according to the estimated SINR of the uplink and the firstadjustment amount of the SINR of the uplink. According to an embodimentof the invention, the effective SINR of the uplink is calculatedaccording to the following formula:

SINR_eff_(uplink)=SINR_est_(uplink)+SINR_per_(uplink), whereinSINR_eff_(uplink) represents the effective SINR of the uplink,SINR_est_(uplink) represents the estimated SINR of the uplink, andSINR_per_(uplink) represents the first adjustment amount of the SINR ofthe uplink.

In block S204, determining a modulation coding scheme of thecommunication link according to the effective SINR of the communicationlink. Those skilled in the art should appreciate that, determining amodulation coding scheme of an uplink and a downlink based on SINRbelongs to common knowledge in the art, which can be obtained viavarious public approaches. The following merely provides an example ofdetermining modulation coding scheme of an uplink and a downlink basedon effective SINR. As shown in Table 1, for each modulation codingscheme, there is an enter effective SINR and a leave effective SINR. Forexample, 64QAM1/2 has an enter effective SINR of 21 dB and a leaveeffective SINR of 18 dB, i.e., in case that current modulation codingscheme is 16QAM1/2, when the effective SINR is greater than 21 dB, themodulation coding scheme will be adjusted to 64QAM1/2. In case thatcurrent modulation coding scheme is 64QAM1/2, when the effective SINR isless than 18 dB, the modulation coding scheme will be adjusted to16QAM1/2.

TABLE 1 Modulation Coding Scheme Enter SINR Leave SINR QPSK 1/2 Min 10016QAM 1/2 15 12 64QAM 1/2 21 18 64QAM 2/3 24 21 64QAM 3/4 27 24

The effective SINR of a communication link according to embodiments ofthe invention takes into consideration influence of PER in actualinterference environment on the estimated SINR, and flexibly adjusts theestimated SINR, so as to select an appropriate modulation coding schemefor user terminal.

According to an embodiment of the invention, further comprising:detecting a feedback status of the uplink and the downlink of the userterminal; setting a second adjustment amount of the SINR of the uplinkand the downlink according to the feedback status of the uplink and thedownlink; wherein the calculating an effective SINR of the communicationlink according to the estimated SINR of the communication link and thefirst adjustment amount of the SINR of the communication link comprises:calculating the effective SINR of the communication link according tothe estimated SINR of the communication link, the first adjustmentamount of the SINR of the communication link and the second adjustmentamount of the SINR of the uplink and the downlink.

Since information such as estimated SINR and PER of a downlink needs tobe calculated by a terminal and fed back to a base station, the basestation needs to set control messages for querying these information,wherein the base station sends a request message, and the terminal feedsback a response message; according to an embodiment of the invention,the second adjustment amount of the SINR of the uplink and the downlinkis set according to the feedback status of the message. Specifically,the detecting a feedback status of the communication link of the userterminal comprises: sending a data request message to the user terminal;setting the second adjustment amount of the SINR of the uplink and thedownlink as 0, in response to receiving a data request packet from theuser terminal before a predetermined time; setting the second adjustmentamount of the SINR of the uplink and the downlink as a negative value,in response to not receiving the data request packet sent by the userterminal before the predetermined time.

According to an embodiment of the invention, for case of the downlink,further comprises: detecting a feedback status of the uplink and thedownlink of the user terminal; setting the second adjustment amount ofthe SINR of the uplink and the downlink according to the feedback statusof the uplink and the downlink; calculating the effective SINR of thedownlink according to the estimated SINR of the downlink, the firstadjustment amount of the SINR of the downlink and the second adjustmentamount of the SINR of the uplink and the downlink.

According to an embodiment of the invention, the formula for calculatingthe effective SINR of the downlink according to the estimated SINR ofthe downlink, the first adjustment amount of the SINR of the downlinkand the second adjustment amount of the SINR of the uplink and thedownlink is shown as follows:

SINR_eff_(downlink)=SINR_est_(downlink)+SINR_per_(downlink)+SINR_fd_(uplink&downlink),wherein SINR_eff_(downlink) represents the effective SINR of thedownlink, SINR_est_(downlink) represents the estimated SINR of thedownlink, SINR_(—) per_(downlink) represents the first adjustment amountof the SINR of the downlink, SINR_fd_(uplink&downlink) represents thesecond adjustment amount of the SINR of the uplink and the downlink.

According to an embodiment of the invention, for case of the uplink,further comprises: detecting a feedback status of the uplink and thedownlink of the user terminal; setting the second adjustment amount ofthe SINR of the uplink and the downlink according to the feedback statusof the uplink and the downlink, wherein for detailed implementationmethod for detecting the feedback status and setting the secondadjustment amount of the SINR, reference may be made to the abovedescription, which will not be repeated here for brevity; calculatingthe effective SINR of the uplink according to the estimated SINR of theuplink, the first adjustment amount of the SINR of the uplink and thesecond adjustment amount of the SINR of the uplink and the downlink.

According to an embodiment of the invention, the formula for calculatingthe effective SINR of the uplink according to the estimated SINR of theuplink, the first adjustment amount of the SINR of the uplink and thesecond adjustment amount of the SINR of the uplink and the downlink isshown as follows:

SINR_eff_(uplink)=SINR_est_(uplink)+SINR_per_(uplink)+SINR_fd_(uplink&downlink),wherein SINR_eff_(uplink) represents the effective SINR of the uplink,SINR_est_(uplink) represents the estimated SINR of the uplink,SINR_per_(uplink) represents the first adjustment amount of the SINR ofthe uplink, SINR_fd_(uplink&downlink) represents the second adjustmentamount of the SINR of the uplink and the downlink.

The method according to the above embodiments, on basis of taking intoconsideration influence of stability of actual interference environmenton the estimated SINR, also takes into consideration influence ofcommunication quality of the wireless link on the estimated SINR, suchthat the effective SINR is more close to real value, thus selects a moreappropriate modulation coding scheme for the user terminal.

According to an embodiment of the invention, further comprises:obtaining a service type of the communication link of the user terminal;setting a third adjustment amount of the SINR of the communication linkaccording to the service type of the communication link; wherein thecalculating the effective SINR of the communication link according tothe estimated SINR of the communication link, the first adjustmentamount of the SINR of the communication link and the second adjustmentamount of the SINR of the uplink and the downlink comprises: calculatingthe effective SINR of the communication link according to the estimatedSINR of the communication link, the first adjustment amount of the SINRof the communication link, the second adjustment amount of the SINR ofthe uplink and the downlink, and the third adjustment amount of the SINRof the communication link.

According to an embodiment of the invention, for case of the downlink,further comprises: obtaining a service type of the downlink of the userterminal; setting a third adjustment amount of the SINR of the downlinkaccording to the service type of the downlink; calculating the effectiveSINR of the downlink according to the estimated SINR of the downlink,the first adjustment amount of the SINR of the downlink, the secondadjustment amount of the SINR of the uplink and the downlink, and thethird adjustment amount of the SINR of the uplink; determining amodulation coding scheme of the uplink according to the effective SINRof the downlink.

According to an embodiment of the invention, the formula for calculatingthe effective SINR of the downlink according to the estimated SINR ofthe downlink, the first adjustment amount of the SINR of the downlink,the second adjustment amount of the SINR of the uplink and the downlink,and the third adjustment amount of the SINR of the uplink is shown asfollows:

SINR_eff_(downlink)=SINR_est_(downlink)+SINR_per_(downlink)+SINR_fd_(uplink&downlink)+SINR_st_(downlink),wherein SINR_eff_(downlink) represents the effective SINR of thedownlink, SINR_est_(downlink) represents the estimated SINR of thedownlink, SINR_per_(downlink) represents the first adjustment amount ofthe SINR of the downlink, SINR_fd_(uplink&downlink) represents thesecond adjustment amount of the SINR of the uplink and the downlink, andSINR_st_(downlink) represents the third adjustment amount of the SINR ofthe downlink.

According to an embodiment of the invention, for case of the uplink,further comprises: obtaining a service type of the uplink of the userterminal; setting a third adjustment amount of the SINR of the uplinkaccording to the service type of the uplink; calculating the effectiveSINR of the uplink according to the estimated SINR of the uplink, thefirst adjustment amount of the SINR of the uplink, the second adjustmentamount of the SINR of the uplink and the downlink, and the thirdadjustment amount of the SINR of the uplink; determining a modulationcoding scheme of the uplink according to the effective SINR of theuplink.

According to an embodiment of the invention, the formula for calculatingthe effective SINR of the uplink according to the estimated SINR of theuplink, the first adjustment amount of the SINR of the uplink, thesecond adjustment amount of the SINR of the uplink and the downlink, andthe third adjustment amount of the SINR of the uplink is shown asfollows:

SINR_eff_(uplink)=SINR_est_(uplink)+SINR_per_(uplink)+SINR_fd_(uplink&downlink)+SINR_st_(uplink),wherein SINR_eff_(uplink) represents the effective SINR of the uplink,SINR_est_(uplink) represents the estimated SINR of the uplink,SINR_per_(uplink) represents the first adjustment amount of the SINR ofthe uplink, SINR_fd_(uplink&downlink) represents the second adjustmentamount of the SINR of the uplink and the downlink, SINR_st_(uplink)represents the third adjustment amount of the SINR of the uplink.

The setting a third adjustment amount of the SINR of the communicationlink according to the service type of the communication link comprises:performing positive adjustment on the third adjustment amount of theSINR of the communication link relative to a base value, in response tothe service type of the communication link is a service type that isdata transmission rate first; performing negative adjustment on thethird adjustment amount of the SINR of the communication link relativeto the base value, in response to the service type of the communicationlink is a service type that is stability first; setting the thirdadjustment amount of the SINR of the communication link as the basevalue, in response to the service type of the communication link is aservice type giving consideration to both data transmission rate andstability.

According to an embodiment of the invention, for case of the downlink,setting the third adjustment amount of the SINR of the downlinkaccording to the service type of the downlink comprises: performingpositive adjustment on the third adjustment amount of the SINR of thedownlink relative to a base value, in response to the service type ofthe downlink is a service type service type that is data transmissionrate first; performing negative adjustment on the third adjustmentamount of the SINR of the downlink relative to the base value, inresponse to the service type of the downlink is a service type that isstability first; setting the third adjustment amount of the SINR of thedownlink as the base value, in response to the service type of thedownlink is a service type giving consideration to both datatransmission rate and stability.

According to an embodiment of the invention, for case of the uplink,setting the third adjustment amount of the SINR of the uplink accordingto the service type of the uplink comprises: performing positiveadjustment on the third adjustment amount of the SINR of the uplinkrelative to a base value, in response to the service type of the uplinkis a service type that is data transmission rate first; performingnegative adjustment the third adjustment amount of the SINR of theuplink relative to the base value, in response to the service type ofthe uplink is a service type that is stability first; setting the thirdadjustment amount of the SINR of the uplink as the base value, inresponse to the service type of the uplink is a service type givingconsideration to both data transmission rate and stability.

Different upper layer service types (e.g., voice, video, or filetransfer, etc.) have different degrees of tolerance to system'sreal-time performance or PER; therefore, the third adjustment amount ofthe SINR of the uplink and the downlink needs to be set according toupper layer service type. For service that is data transmission ratefirst, for example, file transfer service, as it is neither sensitive toPER nor to real-time performance, positive adjustment may be performedon the third adjustment amount of the SINR of the uplink and thedownlink relative to the base value, for example, set as 2 dB, so thatthe system is operated in a relatively high modulation coding scheme toensure data rate and whole system capacity. For service type that isstability first, for example, video service sensitive to PER, very lowPER is needed to ensure fluency of the video; therefore, negativeadjustment may be performed on the third adjustment amount of the SINRof the uplink and the downlink relative to the base value, for example,set to −2 dB, so that the system is operated in a relatively lowmodulation coding scheme to ensure PER. For some service types that needto give consideration to both data transmission rate and stability, thethird adjustment amount of the SINR of the uplink and the downlink maybe set as the base value, for example, 0 dB, to obtain compromisedperformance. Coding adjustment mechanism of existing system does notconsider differences among different service applications. The methodaccording to embodiments of the invention, on basis of taking intoconsideration influence of stability and communication quality of actualinterference environment on the estimated SINR, also takes intoconsideration influence of user's current service demand on theestimated SINR, thereby selecting a more appropriate modulation codingscheme for the user terminal.

Various embodiments for implementing the method of the invention havebeen described hereinabove with reference to accompanying drawings.Those skilled in the art will appreciate that, the above method may beimplemented in software or in hardware at base station side, or beimplemented in a combination of software and hardware. In addition,those skilled in the art will appreciate that, by implementingrespective operations of the above method in software, hardware or acombination thereof, an adaptive modulation coding apparatus can beprovided. Although the apparatus is the same as a general purposeprocessing device in hardware structure, due to function of the softwarecontained therein, the apparatus presents features distinctive from thegeneral purpose processing device, thereby forming the apparatusaccording to embodiments of the invention.

Based on a same inventive concept, the present invention also sets forthan adaptive modulation coding apparatus. FIG. 3 shows an adaptivemodulation coding apparatus 300 according to an embodiment of theinvention, comprising: a first obtaining module 301 configured to obtainan estimated signal-to-interference-plus-noise ratio (SINR) and a packeterror rate (PER) of a communication link of a user terminal; a firstsetting module 302 configured to set a first adjustment amount of theSINR of the communication link according to the PER of the communicationlink; a calculating module 303 configured to calculate an effective SINRof the communication link according to the estimated SINR of thecommunication link and the first adjustment amount of the SINR of thecommunication link; a determining module 304 configured to determine amodulation coding scheme of the communication link according to theeffective SINR of the communication link. The adaptive modulation codingapparatus according to the embodiment of the present invention can beimplemented at base station side.

According to an embodiment of the invention, further comprising: adetecting module configured to detect a feedback status of thecommunication link of the user terminal; a second setting moduleconfigured to set a second adjustment amount of SINR of an uplink anddownlink according to the feedback status of the communication link,wherein the calculating module is further configured to: calculate theeffective SINR of the communication link according to the estimated SINRof the communication link, the first adjustment amount of the SINR ofthe communication link and the second adjustment amount of the SINR ofthe uplink and downlink.

According to an embodiment of the invention, the detecting module isfurther configured to: send a data request message to the user terminal;set the second adjustment amount of the SINR of the uplink and downlinkas 0, in response to receiving a data request packet from the userterminal before a predetermined time; set the second adjustment amountof the SINR of the uplink and downlink as a negative value, in responseto not receiving the data request packet sent by the user terminalbefore the predetermined time.

According to an embodiment of the invention, further comprising: asecond obtaining module configured to obtain a service type of thedownlink of the user terminal; a third setting module configured to seta third adjustment amount of the SINR of the communication linkaccording to the service type of the communication link; wherein thecalculating module is further configured to: calculate the effectiveSINR of the communication link according to the estimated SINR of thecommunication link, the first adjustment amount of the SINR of thecommunication link, the second adjustment amount of the SINR of theuplink and downlink, and the third adjustment amount of the SINR of thecommunication link.

According to an embodiment of the invention, the third setting module isfurther configured to: perform positive adjustment on the thirdadjustment amount of the SINR of the communication link relative to abase value, in response to the service type of the communication link isa service type that is data transmission rate first; perform negativeadjustment on the third adjustment amount of the SINR of thecommunication link relative to the base value, in response to theservice type of the communication link is a service type that isstability first; set the third adjustment amount of the SINR of thecommunication link as the base value, in response to the service type ofthe communication link is a service type giving consideration to bothdata transmission rate and stability.

According to an embodiment of the invention, the communication linkcomprises at least one of the uplink and the downlink.

For detailed implementation of each of the above modules, reference maybe made to the detailed description in the adaptive modulation codingmethod according to embodiments of the invention, which will not berepeated here for brevity.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. An adaptive modulation coding method, comprising:obtaining an estimated signal-to-interference-plus-noise ratio (SINR)and a packet error rate (PER) of a communication link of a userterminal; setting a first adjustment amount of the SINR of thecommunication link according to the PER of the communication link,wherein the first adjustment amount is an accumulative adjustment on theestimated SINR; calculating an effective SINR of the communication linkaccording to the estimated SINR of the communication link and the firstadjustment amount of the SINR of the communication link, wherein theeffective SINR reflect a flexibly adjusted estimated SINR to enableselection of an appropriate modulating coding scheme in a wirelesscommunication environment; detecting a feedback status of thecommunication link of the user terminal: sending a data request messageto the user terminal; setting a second adjustment amount of the SINR ofuplink and downlink as 0, in response to receiving a data request packetfrom the user terminal before a predetermined time; setting the secondadjustment amount of the SINR of the uplink and the downlink as anegative value, in response to not receiving the data request packetsent by the user terminal before the predetermined time; setting thesecond adjustment amount of the SINR of the uplink and the downlinkaccording to the feedback status of the communication link; calculatingthe effective SINR of the communication link according to the estimatedSINR of the communication link and the second adjustment amount of theSINR of the uplink and the downlink; and determining the appropriatemodulation coding scheme of the communication link according to theeffective SINR of the communication link.
 2. The method according toclaim 1, further comprising: obtaining a service type of thecommunication link of the user terminal; setting a third adjustmentamount of the SINR of the communication link according to the servicetype of the communication link; wherein the calculating the effectiveSINR of the communication link according to the estimated SINR of thecommunication link, the first adjustment amount of the SINR of thecommunication link and the second adjustment amount of the SINR of theuplink and the downlink comprises calculating the effective SINR of thecommunication link according to the estimated SINR of the communicationlink, the first adjustment amount of the SINR of the communication link,the second adjustment amount of the SINR of the uplink and the downlink,and the third adjustment amount of the SINR of the communication link.3. The method according to claim 2, wherein the setting a thirdadjustment amount of the SINR of the communication link according to theservice type of the communication link comprises: performing positiveadjustment on the third adjustment amount of the SINR of thecommunication link relative to a base value, in response to the servicetype of the communication link is a service type that is datatransmission rate first; performing negative adjustment on the thirdadjustment amount of the SINR of the communication link relative to thebase value, in response to the service type of the communication link isa service type that is stability first; and setting the third adjustmentamount of the SINR of the communication link as the base value, inresponse to the service type of the communication link is a service typegiving consideration to both data transmission rate and stability. 4.The method according to claim 1, wherein the communication linkcomprises at least one of the uplink and the downlink.